size = int(input("请输入棋盘的大小: "))
for i in range(size):
    for j in range(size) :
        if i==0 and j==0:
            print("┏",end=' ')
        elif i==0 and j==size-1:
            print("┓",end=' ')
        elif i==size-1 and j == 0 :
            print("┗",end=' ')
        elif i==size-1 and j==size-1:
            print("┛",end=' ')
        elif j == 0:
            print("┠",end=' ')
        elif i==size-1:
            print("┷" ,end=' ')
        elif j==size-1:
            print("┨",end=' ')
        elif i == 0:
            print("┯",end=' ')
        else :
            print("┼",end=' ')
    print(' ')